Replaceable emission-condensing unit for a bar code reader

ABSTRACT

A bar-code reader is easy to use and has an optical system that is easy to position and replace. The bar-code reader is used for a POS system. The bar code reader has a laser source for emitting a laser beam, a scan unit for scanning a bar code with the laser beam according to a predetermined scanning pattern, a window for emitting the laser beam from the scan unit, a condensing unit for condensing reflected light returned from the bar code through the window and scan unit along the route the laser beam traced, a photosensor for detecting the condensed light and providing an electric signal in proportion to the intensity of the detected light, and an emission-condensing unit incorporating the laser source, condensing unit, and photosensor, which can be easily and correctly mechanically installed.

This application is a divisional application filed under 37 CFR §1.53(b) of parent application Ser. No. 08/540,887, filed Oct. 11, 1995now U.S. Pat. No. 5,900,615.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a bar-code reader for reading bar codesand optical marks and a POS system employing the bar-code reader.

2. Description of the Related Art

A POS terminal is connected to a bar-code reader to read a bar code on apiece of merchandise. The bar-code reader has an optical reader forreading a bar code and a recognition unit for recognizing the bar code.The optical reader emits a laser beam, according to a predeterminedscanning pattern, to scan a bar code at a high speed, detects the lightreflected from the bar code, and reads the bar code according to thereflected light.

The optical reader has a laser unit for emitting a laser beam, arotating polygon mirror for reflecting the laser beam, a pattern mirrorfor reflecting the deflected laser beam according to a predeterminedscanning pattern, a window for passing the reflected laser beam to theoutside, and a photosensor for detecting the light reflected from a barcode.

The reflected light is guided by the pattern mirror and polygon mirroropposite to the emitted laser beam and is condensed by a condensing lensonto the photosensor. The photosensor provides an electric signal inproportion to the intensity of the condensed light. The output of thephotosensor changes in response to the pattern of the bar code. Therecognition unit processes the electric signal, to decode the bar code.The decoded data is supplied to the POS terminal connected to thebar-code reader.

According to the prior art, the laser unit, polygon mirror, patternmirror, condensing lens, and photosensor are separately fixed to acasing of the bar-code reader.

To correctly scan a bar code, a laser beam of the laser unit must hit apredetermined position on the polygon mirror. To condense reflectedlight from the bar code onto the photosensor through the pattern mirror,polygon mirror, and condensing lens, the condensing lens must becorrectly positioned with respect to the polygon mirror, the distancebetween the condensing lens and the photosensor must be accurately set,and the optical axis of the condensing lens must be aligned with thephotosensor.

If these components are incorrectly positioned, the bar-code reader mayproduce a read error. These components, therefore, must be carefullyinstalled in the bar-code reader by a skilled person.

A laser source in the laser unit has a certain service life, andtherefore, the laser unit must be periodically replaced. Thisreplacement must also be made carefully.

The laser source may be a semiconductor laser. The semiconductor lasersshow different characteristics even under the same driving current.Namely, each semiconductor laser has its own light intensity andwavelength. The bar-code reader is designed to operate with a givencharacteristic of a laser source. Accordingly, the bar-code reader willhave trouble if a replacement laser source has a differentcharacteristic.

To solve this problem, the prior art adjusts a drive circuit for drivinga replacement laser source so that the laser source may provide arequired characteristic. This adjustment must be carried out wheneverthe laser source is replaced. This is laborious and takes a long time.In addition, it is difficult to precisely adjust the replaced lasersource to the required characteristic.

The semiconductor lasers are vulnerable to static electricity.Accordingly, the laser source must be replaced without staticelectricity. To achieve this, time and labor are needed. Even withcareful work, the laser source is sometimes damaged by staticelectricity.

If the photosensor is incorrectly positioned with respect to thecondensing lens, the diameter of a condensed beam will increase. Thewide beam is useless to read the thin bars of a bar code. This problemis serious when the bar-code reader is spaced away from the bar codes tobe read.

The bar-code reader must be easy and convenient to use.

To recognize bargain merchandise, the operator of the bar-code readerattaches a memo listing the bargain merchandise to a space on acheck-out counter. The memo on the check-out counter is usually far fromthe bar-code reader. Accordingly, the operator must alternately look atthe memo and a bar code on merchandise. This is laborious for theoperator.

It is important to minimize power consumption and extend the servicelife of the bar-code reader. For this purpose, the bar-code reader isset in a standby state while it is not reading bar codes. The bar-codereader must automatically be activated before reading bar codes.

To prevent shoplifting, each piece of merchandise is provided with amagnetic tag, which is nullified after the merchandise is paid at thecheck-out counter. If the merchandise is illegally brought out, asecurity apparatus at a shop entrance may detect the magnetism of thetag. The bar-code reader and a tag nullification unit are usuallyseparate from each other at the check-out counter, to reduce the workingspace at the check-out counter.

The bar-code reader is connected to a POS terminal through a cable withor without a connector. The connector may come off the bar-code reader,and the cable may interfere with the operator.

After reading a bar code, the bar-code reader makes a sound to informthe operator of the completion of reading the bar code. To pass thesound, the casing of the bar-code reader has a speaker hole. The speakerhole may guide water into the bar-code reader, to damage the bar-codereader.

A keyboard of the POS terminal is usually placed on top of a tallbar-code reader. The operator must then extend his or her hands to thekeyboard. This puts a strain on the operator.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide a bar-code readerhaving an optical system that is easy to position and replace, therebyreducing adjustment work.

A second object of the present invention is to provide a bar-code readercapable of reading thin bars in a bar code irrespective of the positionof the bar code.

A third object of the present invention is to provide a bar-code readercapable of showing an operator various pieces of information withoutforcing the operator to move his or her eyes far.

A fourth object of the present invention is to provide a bar-code readerthat is put in a standby state when no bar codes are being read and isautomatically and quickly put in a ready state to read bar codes.

A fifth object of the present invention is to provide a bar-code readercapable of nullifying tags, in a small space, with ease.

A sixth object of the present invention is to provide a bar-code readerhaving a cable that cannot come off or interfere with an operator.

A seventh object of the present invention is to provide a bar-codereader capable of generating a sound, of sufficient volume, to inform anoperator of the completion of reading a bar code without the casing ofthe bar-code reader having a speaker hole.

An eighth object of the present invention is to provide a bar-codereader with a keyboard, placed thereon, which is easy to manipulate.

A ninth object of the present invention is to provide a POS systemcapable of showing an operator various pieces of information.

To accomplish the first object, a first aspect of the present inventionprovides a bar-code reader having a laser source for emitting a laserbeam, a scan unit for scanning a bar code with the laser beam accordingto a predetermined scanning pattern, a window for passing the laser beamfrom the scan unit toward the bar code that is present or being moved inthe vicinity of the window, a condensing unit for condensing reflectedlight returned from the bar code through the window and scan unit alongthe route the laser beam traced, and a photosensor for detecting thecondensed light and providing an electric signal in proportion to theintensity of the detected light. The laser source, condensing unit, andphotosensor are collectively incorporated in an emission-condensing unitthat is mechanically precisely positioned.

The laser source and optical system are adjusted so that theemission-condensing unit may emit a laser beam at a predeterminedposition in a predetermined direction. The condensing unit andphotosensor in the emission-condensing unit are adjusted to return thereflected light from the bar code opposite to the emitted laser beam.These components are easy to adjust. The emission-condensing unit as awhole is easy to replace.

The photosensor is arranged on an extension of the optical axis of alaser beam emitted from the emission-condensing unit, to realize easyadjustment and reduce installation errors.

The emission-condensing unit includes a circuit board, which supportsthe laser source, a drive circuit for driving the laser source, thephotosensor, and a detection circuit for receiving and processing anelectric signal from the photosensor. The intensity of the electricsignal of the photosensor is determined by the intensity of detectedlight and the sensitivity of the detection circuit. In theemission-condensing unit, the relationship between the intensity of alaser beam emitted from the laser source and the sensitivity of thedetection circuit is fixed in advance, to provide a stabilized electricsignal without adjustment even if the emission-condensing unit isreplaced.

The emission-condensing unit may have a light source unit thatincorporates the laser source and a shaping lens for shaping a laserbeam from the laser source.

The laser source may be a semiconductor laser, and the light source unitmay incorporate the laser source and a temperature sensor for detectingthe temperature of the semiconductor laser. This arrangement is capableof correctly estimating the service life of the laser source. Accordingto the estimation, the laser source is replaced in a timely manner. Thetemperatures and ON periods of the laser source are recorded, to providedata about the service life of the laser source. The data is used toprecisely analyze the service life of the laser source.

To accomplish the second object, a second aspect of the presentinvention provides a bar-code reader having a photosensor arrangedcloser to a condensing unit from a position where an object on thefarthest edge of the readable range of the bar-code reader forms animage. Even if a bar code takes different positions, the diameter of acondensed beam on the photosensor will not be increased, and therefore,thin bars in the bar code will be readable.

To accomplish the third object, a third aspect of the present inventionprovides a bar-code reader having a memo holder adjacent to a window ofa casing of the bar-code reader. The memo holder may be a metal plate tohold a memo with a magnet removably attached to the metal plate. Thememo holder may be an insertion unit having an opening. A memo isinserted into the insertion unit and is seen through the opening. Anoperator can carry out a bar-code reading operation and read the memowithout moving his or her eyes much.

To accomplish the fourth object, a fourth aspect of the presentinvention provides a bar-code reader having an environmental lightdetector for detecting a change in the intensity of the environmentallight. The light detector is arranged on a casing of the bar-code readeron an extension of the center line of a window for passing a laser beamemitted from a scan unit. The environmental light detector is on theside of the window where an article having a bar code starts to moveacross the window. The bar code reader also has a controller for turningON a laser source when the change in the detected intensity ofenvironmental light is above a predetermined value. Since theenvironmental light detector is on the starting side of the window, anyarticle crosses the environmental light detector before its bar code isread. Accordingly, the environmental light detector surely detects thepresence of the article and instantaneously turns ON the laser source tosurely read the bar code. When no bar code is being read, the lasersource is turned OFF to reduce power consumption and elongate theservice life.

To accomplish the fifth object of the present invention, a fifth aspectof the present invention provides a bar-code reader having anullification unit for nullifying a tag for preventing shoplifting. Thenullification unit is arranged beside a window on a route traced by anarticle having a bar code to be read. This arrangement reads the barcode of an article and then nullifies a tag attached to the article. Thenullification unit is higher than the window of the bar-code reader, sothat there is no need to lift an article when reading a bar code on thearticle. This improves operability. The nullification unit may beinclined to further improve the operability.

To accomplish the sixth object of the present invention, a sixth aspectof the present invention provides a bar-code reader having at least onecable that extends directly or through a connector from the back of acasing of the bar-code reader. The cable is covered with a cable coverthat is removably attached to the back of the casing. The cable coverprevents the cable from coming off the casing. The cable cover may havea plurality of cable holes so that the cable is guided outside throughone of the holes irrespective of the installation situation of thebar-code reader. The back of the casing may have a cable recess toaccommodate the cable. The cable is fixed in the cable recess withfixing units.

To accomplish the seventh object of the present invention, a seventhaspect of the present invention provides a bar-code reader having acover. The cover is attached to the bar-code reader, to entirely coverthe bar-code reader. The cover has an opening for a window of thebar-code reader. The bar-code reader has a buzzer that faces the cover.A sound from the buzzer resonates in a space formed between the bar-codereader and the cover and goes outside. Due to the resonation, the soundis sufficiently large without buzzer holes. The buzzer may be selectedfrom a plurality of buzzers having different wavelengths, so that thebuzzer sound is distinguishable from others generated by adjacentbar-code readers.

To accomplish the eighth object of the present invention, an eighthaspect of the present invention provides a bar-code reader having alaser source for emitting a laser beam, a scan unit for scanning a barcode with the laser beam according to a predetermined scanning pattern,a window, a condensing unit for condensing reflected light returned fromthe bar code through the window and scan unit along the same path theemitted laser beam traced, and a photosensor for detecting the condensedlaser beam and providing an electric signal in proportion to theintensity of the detected laser beam. The laser source, condensing unit,and scan unit are horizontally arranged to reduce the height of thebar-code reader.

To accomplish the ninth object of the present invention, a ninth aspectof the present invention provides a POS system having a bar-code readerand an information processing unit. The bar-code reader has a casing, awindow, and a display unit arranged adjacent to the window. Theinformation processing unit has a merchandise file for storingmerchandise information and a retrieval unit for retrieving merchandiseinformation from the merchandise file according to bar-code dataprovided by the bar-code reader. The retrieved information istransferred to the bar-code reader. The bar-code reader displays theinformation on the display unit. This arrangement is capable ofdisplaying information about a bar code just read. The displayedinformation is easy for an operator to see.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from thedescription as set forth below with reference to the accompanyingdrawings, in which:

FIG. 1 is a perspective view showing a bar-code reader according to aprior art;

FIG. 2 shows laser beam scanning patterns;

FIG. 3 is a sectional view showing a unitized bar-code reader accordingto a prior art;

FIG. 4 is a perspective view showing a bar-code reader according to afirst embodiment of the present invention;

FIG. 5 shows an emission-condensing unit of the first embodiment;

FIGS. 6A and 6B show a light source unit of the first embodiment;

FIGS. 7A and 7B shows the paths of an emitted beam and reflected lightin the emission-condensing unit;

FIG. 8A show different image forming positions of reflected light withrespect to different bar-code positions according to the presentinvention;

FIGS. 8B and 8C show different image forming positions of reflectedlight with respect to different bar-code positions according to theprior art;

FIG. 9 shows a change in the diameter of a condensed beam in response toa change in the position of a bar code;

FIG. 10 shows the relationship between a condensed beam and aphotosensor when the photosensor is positioned at a distal end of abar-code readable range;

FIG. 11 shows changes in the diameter of a condensed beam based on therelationship of FIG. 10;

FIG. 12 shows a change in the intensity of light detected by thephotosensor according to a change in a bar-code read position;

FIG. 13 shows a bar-code reader according to a second embodiment of thepresent invention, having a metal plate beside a window to hold a memowith a magnet.

FIG. 14 shows a bar-code reader according to a third embodiment of thepresent invention, having a memo insertion unit beside a window;

FIG. 15 is a sectional view showing the memo insertion unit of the thirdembodiment;

FIG. 16 shows a bar-code reader according to a fourth embodiment of thepresent invention, having a display unit for displaying information sentfrom a POS system and a restart sensor for turning ON a laser source;

FIGS. 17A and 17B are flowcharts showing a flow of data in the bar-codereader and POS terminal according to the fourth embodiment;

FIG. 18 shows a bar-code reader and a nullification unit separatelyarranged on a check-out counter according to a prior art;

FIGS. 19A and 19B show a bar-code reader with a nullification unitaccording to a prior art;

FIG. 20 shows a bar-code reader according to a fifth embodiment of thepresent invention, having a nullification unit beside a window;

FIG. 21 shows a piece of merchandise moved along the bar-code reader ofthe fifth embodiment;

FIG. 22 shows a bar-code reader according to a sixth embodiment of thepresent invention, having a nullification unit of another type;

FIG. 23 shows a piece of merchandise moved along the bar-code reader ofthe sixth embodiment;

FIG. 24 shows a nullification unit according to a seventh embodiment ofthe present invention;

FIG. 25 shows the back of a bar-code reader according to an eighthembodiment of the present invention;

FIG. 26 shows a cable of the bar-code reader of the eighth embodiment;

FIG. 27 shows a bar-code reader according to a prior art, having aspeaker hole on the surface of the bar-code reader;

FIG. 28 shows a bar-code reader according to a ninth embodiment of thepresent invention, having a cover and a buzzer installed on a main body;

FIG. 29 is a sectional view showing the ninth embodiment;

FIG. 30 shows the wavelength characteristic of a buzzer sound of theninth embodiment;

FIG. 31 shows buzzers according to a tenth embodiment of the presentinvention;

FIG. 32 shows the wavelength characteristics of buzzer sounds accordingto the tenth embodiment;

FIG. 33 shows a bar-code reader according to an 11th embodiment of thepresent invention, having buzzers and a cover;

FIG. 34 shows a bar-code reader according to a prior art arranged on acheck-out counter;

FIG. 35 shows a bar-code reader according to a 12th embodiment of thepresent invention arranged on a checkout counter;

FIGS. 36A and 36B show a POS terminal according to a prior art; and

FIGS. 37A and 37B show a POS terminal according to a 13th embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before proceeding to a detailed description of the preferred embodimentsof the present invention, a conventional bar-code reader will bedescribed below for a clearer understanding of the differences betweenthe present invention and the prior art.

FIG. 1 shows the conventional bar-code reader. The bar-code reader has alaser unit 2 such as a laser tube for emitting a laser beam. A reflector3 reflects the laser beam toward a polygon mirror 4. The polygon mirror4 is rotated at a high speed by a motor 5. The side faces of the polygonmirror 4 have mirrors to reflect the laser beam from the reflector 3 andprovide a scan beam. A pattern mirror 6 reflects the scan beam upwardly.This beam is passed through a window 9, to scan a bar code. Reflectedlight from the bar code enters the bar-code reader through the window 9.

FIG. 2 shows an example of a scanning pattern of a laser beam at aposition for scanning a bar code. The polygon mirror 4 and patternmirror 6 are adjusted to provide such a scanning pattern.

The reflected light from the bar code is reflected by the pattern mirror6 and polygon mirror 4 and is condensed by a condensing lens 7. Thecondensed light is made incident to a photosensor 8. The photosensor 8and a controller (not shown) are mounted on a printed board 10. Inproportion to the intensity of the light, the photosensor 8 generates anelectric signal. According to the electric signal, the controllerdecodes the bar code and transfers the decoded data to an external POSterminal.

The photosensor 8 is adjusted to a position where the condensing lens 7focuses reflected light.

FIG. 3 is a sectional view showing the bar-code reader of the prior art.

The laser unit 2, reflector 3, condensing lens 7, and photosensor 8 areseparately incorporated in a casing 101 of the bar-code reader.

To scan a bar code with a laser beam emitted from the laser unit 2 andreflected by the polygon mirror 4, the laser unit 2 and reflector 3 mustbe correctly positioned with respect to each other, so that the laserbeam is made incident to a predetermined position on the polygon mirror4. To receive reflected light from the bar code by the pattern mirror 6and polygon mirror 4 and focus the reflected light on the photosensor 8through the condensing lens 7, the position of the polygon mirror 4 withrespect to the condensing lens 7, the distance between the condensinglens 7 and the photosensor 8, and the position of the optical axis ofthe condensing lens 7 with respect to the photosensor 8 must becorrectly set. In addition, the route of the laser beam must beadjusted. The condensing lens 7 may be a condensing mirror.

If these components are incorrectly positioned, a read error will occur.Accordingly, these components must be carefully positioned by a skilledworker.

FIG. 4 is a perspective view showing a bar-code reader according to thefirst embodiment of the present invention. An emission-condensing unit 1includes a laser unit 2, reflectors 31 and 32, a condensing lens 7, anda photosensor 8. The other parts of this embodiment are the same asthose of the prior art of FIG. 1.

FIG. 5 shows the details of the emission-condensing unit 1. The unit 1is a combination of a part for emitting a laser beam and a part forcondensing and detecting reflected light from a bar code.

A printed board 12 supports the laser unit 2 and photosensor 8, and abase 11 supports the condensing lens 7, reflectors 31 and 32, andprinted board 12.

FIG. 6A is a sectional view showing the laser unit 2. The laser unit 2has a laser source 21 such as a semiconductor laser for emitting a laserbeam, a shaping lens 22 for shaping and focusing the laser beam, a heatsink 24 for radiating heat generated by the laser source 21, and atemperature sensor 25 for detecting the temperature of the laser source21. To focus the laser beam from the laser source 21 on a predeterminedposition, the distance between the laser source 21 and the shaping lens22 must be set to a predetermined value. Since these components arefixed in the laser unit 2, there is no need to adjust the distancebetween the laser source 21 and the shaping lens 22 when the unit 2 isreplaced.

FIG. 6B shows a circuit for determining an ON time of the laser source21 and processing the temperature provided by the temperature sensor 25.

A drive circuit 26 of the laser source 21 provides ON information aboutthe laser source 21. A temperature detection circuit 27 processes theoutput of the temperature sensor 25 and provides a detected temperature.A life judgement circuit 28 determines whether or not the laser source21 has reached a set life according to the ON information from the drivecircuit 26, the temperature from the temperature detection circuit 27,and reference life data. If the life judgement circuit 28 determinesthat the laser source 21 has reached the end of its life, a buzzer 281and a lamp 282 generate an alarm to let an operator replace theemission-condensing unit 1. A data record circuit 29 records the ONinformation and temperature information. The information stored in thedata record circuit 29 is used to analyze the life of the replaced lasersource. A result of the analysis is used to more precisely predict thelife of a laser source.

The prior art determines the life of a semiconductor laser according toonly the ON time of the semiconductor laser. In practice, however, thelife of a semiconductor laser is also influenced by the temperaturethereof. Accordingly, the present invention employs the ON time as wellas the temperature of a semiconductor laser, to correctly determine thelife thereof.

The laser source 21 and the drive circuit 26 are integrated together onthe printed board 12. Accordingly, it is not necessary to adjust thedrive circuit 26 when the laser unit 2 is replaced. The drive circuit 26is covered with a metal shield to prevent damage from staticelectricity.

The photosensor 8 detects light reflected by a bar code and condensed bythe condensing lens 7. The photosensor 8 is fixed to a predeterminedposition on the printed board 12 and is connected to a detection circuit(not shown) mounted on the printed board 12.

A switch 31 is used to turn ON/OFF a power source of the bar-codereader.

An indicator 32 has, for example, two LEDs. The indicator 32 is used toinform an operator whether or not a bar code has been correctly read. Ifa read error occurs, the operator of the bar-code reader must repeat theread operation of the bar code. One of the LEDs is turned ON when a barcode is correctly read, and the other is turned ON when a read erroroccurs. The printed board 12 includes a control circuit for controllingthe ON/OFF operation of the LEDs according to a result of reading a barcode. The number of the LEDs is not limited to two. It may be one,three, or more.

An environmental light sensor 33 detects the intensity of light aroundthe bar-code reader and serves as a restart sensor.

To read a bar code, the laser source 21 must be turned ON, and the motor5 must be driven to turn the polygon mirror 4. Always activating thelaser source 21 and motor 5 wastes power. It is required to minimizepower consumption while no bar code is being read.

The service life of the semiconductor laser is relatively short. Thesemiconductor laser will shortly be exhausted if it is continuouslyactivated. To extend the service life of the laser source, it isnecessary to turn OFF the same when no bar code is being read.

To read a bar code, the operator puts an article or his or her hands onthe bar-code reader. This results in decreasing the intensity ofenvironmental light. Detecting such a decrease may determine the startof a bar-code reading operation. The environmental light sensor 33 isused to detect this kind of change in the intensity of environmentallight.

The environmental light sensor 33 is connected to a detection circuitmounted on the printed board 12. The detection circuit compares theintensity of the environmental light detected by the sensor 33 with athreshold. If the detected intensity is below the threshold, a bar codereading operation must be started, and therefore, the motor 5 is driven.In this way, the sensor 33 is capable of reducing power consumptionwhile no bar code is being read and extending the service life of thelaser source 21.

The condensing lens 7 focuses reflected light from a bar code on thephotosensor 8. The reflectors 31 and 32 reflect a laser beam emitted bythe laser unit 2 toward the polygon mirror 4. The base 11 is made ofresin.

FIGS. 7A and 7B show a laser beam emitted by the laser unit 2, reflectedlight from a bar code, and the positions of the components incorporatedin the emission-condensing unit 1. FIG. 7A is a top view, and FIG. 7B isa side view.

The optical axis of an output beam from the laser unit 2 is aligned withthe optical axis of the reflected light. The output beam from the laserunit 2 is reflected by the reflector 31 by 90 degrees. The laser beamfrom the reflector 31 is reflected by the reflector 32 by about 90degrees in an opposite direction. As a result, the laser beam isdirected toward the polygon mirror 4 along the optical axis a.

Reflected light from a bar code has a certain width and is made incidentto the condensing lens 7. The optical axis of the condensing lens 7 isaligned with the optical axis a. The condensing lens 7 focuses thereflected light on the photosensor 8. The center of the photosensor 8 ison the optical axis a and is positioned at the focal point of thecondensing lens 7, so that the reflected light condensed by thecondensing lens 7 focuses on the photosensor 8.

There is no mirror between the condensing lens 7 and the photosensor 8,so that the light from the condensing lens 7 directly enters thephotosensor 8. The laser unit 2 is on the printed board 12 and is awayfrom the photosensor 8 by a distance L so that the laser unit 2 does notinterfere with the condensed light, and the laser beam from the laserunit 2 does not interfere with the condensing lens 7. The laser unit 2and photosensor 8 are at the same level.

To satisfy the positional relationships of FIGS. 7A and 7B among thecomponents, the laser unit 2 and photosensor 8 are fixed atpredetermined positions on the printed board 12, and the condensing lens7 is arranged on the base 11 so that the optical axis of the condensinglens 7 agrees with the optical axis a.

The reflectors 31 and 32 are attached to each end of an arm 33 made of abent metal plate. The height of the ends of the arm 33 is determinedaccording to the heights of the laser unit 2 and polygon mirror 4. Thedistance between the ends of the arm 33 is equal to the distance L ofFIG. 7A.

The lengths of the base of the lens unit 2 and the arm 33 are determinedto maintain the distance between the condensing lens 7 and thephotosensor 8. The base 11 and printed board 12 are fixed to each otherwith, for example, screws.

With these arrangements, the positions of the components of theemission-condensing unit 1 require no adjustment when the unit 1 isreplaced, thereby improving workability.

The effect of aligning a laser beam from the emission-condensing unit 1with the optical axis of the condensing lens 7 will be explained withreference to FIGS. 8A to 8C in which FIG. 8A shows optical paths of thepresent invention and FIGS. 8B and 8C show optical paths of the priorart.

Each bar-code reader has a readable range. The bar-code reader must beable to read any bar code that is in the readable range. The nearestpoint of the readable range to the window of the bar-code reader is A,the farthest point thereof is C, and the intermediate point thereof isB.

A laser beam from the emission-condensing unit 1 is reflected by thepolygon mirror 4 and pattern mirror 6, to scan a bar code. Irrespectiveof the rotational position of the polygon mirror 4, a scan point on thebar code is on an extension of the laser beam emitted from the unit 1.Accordingly, the points A, B, and C will be on an extension of theoutput laser beam. The laser beam is reflected and scattered by the barcode. Part of the reflected light is reflected by the pattern mirror 6and polygon mirror 4 and is condensed by the condensing lens 7 onto thephotosensor 8, which converts the light into an electric signal. Namely,the condensing lens 7 forms an image of a light spot on the bar code ata position close to the photosensor 8. In FIG. 8A, the output beam fromthe unit 1 agrees with the optical axis of the condensing lens 7.Accordingly, any one of the points A, B, and C is on the optical axis ofthe condensing lens 7. Therefore, the image of any one of the points A,B, and C is formed on the optical axis of the condensing lens 7. Thephotosensor 8 arranged on the optical axis of the condensing lens 7efficiently catches the condensed light.

According to the prior art of FIG. 8B, an output beam from theemission-condensing unit 1 is in parallel with and away from the opticalaxis of the condensing lens 7. According to the prior art of FIG. 8C, anoutput beam from the unit 1 intersects the optical axis of thecondensing lens 7 at the intermediate point B. A main beam from any oneof the points A, B, and C passing through the center of the condensinglens 7 has an inclination with respect to the optical axis of thecondensing lens 7 in FIGS. 8B and 8C. Accordingly, the image of any oneof the points A to C of the prior art vertically varies, and therefore,the photosensor 8 is unable to correctly read the image.

The position of the optical axis of the photosensor 8 will be explained.

FIGS. 9 to 12 show the relationship between the position of a piece ofmerchandise and the focal point of the condensing lens 7.

As shown in FIG. 8A, the nearest point A of the readable range forms animage at a farthest point A' from the condensing lens 7. Theintermediate point B forms an image at an intermediate point B'. Thefarthest point C forms an image at a nearest point C' to the condensinglens 7.

The prior art arranges the photosensor 8 at the intermediate point B'.In this case, the relationship between a reflection point and thediameter of a condensed beam on the photosensor 8 is as shown in FIG. 9.Namely, the diameter of a condensed beam from the point B is smallest onthe photosensor 8 positioned at the point B'. As the reflection pointseparates from the point B, the diameter of the condensed beam enlarges.

The larger the diameter of the condensed beam is, the smaller thedetectable minimum width of a bar decreases. Accordingly, when a barcode is positioned at the point A or C, it is difficult to detect thinbars in the bar code. When the bar code is at the point C farthest fromthe bar-code reader, it is possible to detect only wide bars in the barcode.

FIG. 10 shows the position of the photosensor 8 according to the presentinvention.

The photosensor 8 is closer to the condensing lens 7 than the focaldistance f of the lens 7. FIG. 11 shows the relationship between areflection point and the diameter of a condensed beam in thisarrangement. The diameter of a condensed beam on the photosensor 8 islargest when reflected light comes from the point A nearest to thebar-code reader. The diameter of the condensed light becomes smaller asthe reflection point separates from the bar-code reader, and is smallestat the farthest point C of the readable range.

Since the diameter of the condensed beam becomes smaller as the distancebetween the bar code and the bar-code reader elongates, narrow bars ofthe bar code can be read even if the article is away from the bar-codereader. When the bar code is close to the bar-code reader, the diameterof the condensed beam is large. However, even in this case, bars havinga minimum width are readable.

In this way, the present invention arranges the photosensor 8 at aposition where reflected light from the farthest point of the readablerange forms an image through the condensing lens 7. It is possible toarrange the photosensor 8 closer to the condensing lens 7 from thisposition. For example, the photosensor 8 may be arranged closer to thecondensing lens 7 from the focal point of the lens 7. This arrangementenables the photosensor 8 to correctly read bar codes positioned at thedistal or proximal end of the readable range.

The intensity of the reflected light caught by the photosensor 8 isdetermined by the solid angle at which the condensing lens 7 is visiblefrom a laser beam emission point and the ratio of part of the reflectedlight that enters the photosensor 8 to the total reflected light. Thesolid angle decreases in order of the positions A, B, and C of FIG. 10.The prior art arranges the condensing lens 7 at a position wherereflected light from the position B is focused. Accordingly, the ratioof part of reflected light that enters the photosensor 8 to the totalreflected light is maximum at the position B, and those at the positionsA and C are lower than that. Consequently, the intensity of reflectedlight detected by the photosensor 8 according to the prior art changesas indicated with a dotted line in FIG. 12. On the other hand, thepresent invention arranges the photosensor 8 at a position wherereflected light from the position C is condensed by the condensing lens7. Accordingly, the ratio of part of reflected light that enters thephotosensor 8 to the total reflected light is maximum at the position C.As a result, the intensity of reflected light received by thephotosensor 8 according to the present invention is as indicated by acontinuous line in FIG. 12.

When the intensity of the reflected light received by the photosensor 8is weak, an electric signal generated by the photosensor 8 isincorrectly processed. The bar-code reader must read any bar code in thereadable range. To realize this, the prior art determines a detectablelower limit of the photosensor 8 according to the weakest intensity ofreflected light coming from the position C. Namely, the photosensor 8must be more sensitive. On the other hand, the intensity of lightreceived by the photosensor 8 of the present invention is averaged withrespect to the positions A, B, and C. The intensity of light coming fromany one of these positions and received by the photosensor 8 is largerthan the intensity of light coming from the position C and received bythe prior art. Namely, the sensitivity of the photosensor 8 of thepresent invention may not be so high. One technique of improving thesensitivity of the photosensor 8 is to increase the light receivingarea. This results in increasing the cost of the bar-code reader anddecreasing the response speed. Another technique is to increase theamplification ratio of an electric circuit of the photosensor. Thisresults in increasing noise and read errors.

The operator of the bar-code reader must recognize time-limited discountmerchandise and usual discount merchandise. Accordingly, the operatorusually attaches a memo listing the discount merchandise to a space on acheck-out counter or on a keyboard.

The height of the check-out counter differs from the height of thewindow of the bar-code reader, and the check-out counter is usuallyspaced from the bar-code reader. To read a bar code, the operator looksat the window of the bar-code reader. To check the memo, the operatorlooks at the check-out counter. In this way, the operator must move hisor her eyes between the bar-code reader and the check-out counter. Thisis laborious for the operator.

The memo is simply attached to the check-out counter with an adhesivetape, and therefore, easily comes off.

To solve these problems, a bar-code reader according to the secondembodiment of the present invention has a device for keeping a memo neara window of the bar-code reader so that the operator may easily see thememo.

FIG. 13 is an external view showing the bar-code reader according to thesecond embodiment. The bar-code reader has a metal plate 42 beside awindow 9. A magnet 41 is used to fix a memo 120 on the metal plate 42. Aclip to hold a memo may be attached to the metal plate 42.

In FIG. 13, the window 9 is on the right side, to provide a relativelylarger space on the left side for the memo.

FIG. 14 is an external view showing a bar-code reader according to thethird embodiment of the present invention. The bar-code reader has anopening 43 beside a window 9. A memo 121 is inserted into the opening43. The memo 121 is seen through a window 44, which is covered withtransparent glass or resin to prevent water from soaking the memo 121 ordamaging the inside of the bar-code reader. If the bar-code reader iswaterproof, or if there is no risk of soaking the memo, or if the memois waterproof, the window 44 need not have a glass or resin cover.

FIG. 15 is a sectional view showing a cover 61 of the bar-code reader.The cover 61 has a channel shape. A space 45 is formed between the glass46 and the cover 61. The memo 121 is inserted into the space 45. The topof the cover 61 is provided with the opening 43 for passing the memo 121as shown in FIG. 14. The opening 43 is shaped to easily pass the memo121. The opening 43 may have a lid to hold the memo 121 when thebar-code reader is vertically installed.

In FIG. 14, the cover 61 of the bar-code reader is provided with a passmark 51 of any shape (a triangle in FIG. 14). The pass mark 51 serves asa guide to pass a bar code in front of the bar-code reader. The passmark 51 indicates an optimum position for passing a bar code to be read.

Since articles having bar codes are almost always passed over the passmark 51, the bar-code reader of the third embodiment has anenvironmental light sensor (restart sensor) 33 at the pass mark 51. Whenblocked by articles or hands, the sensor 33 senses a change in theintensity of environmental light. The motion of passing articles differfrom person to person, and therefore, the position of the sensor 33 mustbe carefully selected.

As mentioned above, articles are almost always passed over the mark 51even if there are individual differences. The environmental light sensor33 installed near the mark 51, therefore, surely detects a change in theenvironmental light, to turn ON/OFF the laser source and the motor ofthe polygon mirror.

The installation position of the environmental light sensor 33 is notlimited to near the mark 51. The sensor 33 may be arranged anywhere onthe path for passing articles having bar codes, or a position which isnaturally seen by an operator. It is preferable to arrange the sensor 33on the side of the window of the bar-code reader to where an articlestarts to move across the window.

Since the operator sees the mark 51 whenever he or she passes an articlehaving a bar code over the mark 51, a lamp or a display to show whetheror not the bar code has correctly been read may be installed around themark 51. This arrangement is convenient because the operator may confirmwhether or not a bar code has successfully been read without moving hisor her eyes much.

FIG. 16 shows a bar-code reader according to the fourth embodiment ofthe present invention. This bar-code reader is provided with a displayunit 46 such as a liquid crystal panel on the front surface of thebar-code reader.

FIGS. 17A and 17B show a bar-code reader 100 connected to a POS terminal200, and a flow of data between them. The bar-code reader 100 has abar-code reading unit 101, which transmits bar-code data to the POSterminal 200 through a cable. The bar-code data is received by areceiving unit 201 of the POS terminal 200. According to the bar-codedata, the POS terminal 200 retrieves a commodity name, price, etc., froma merchandise file 204.

FIG. 17A shows a flow of data according to the prior art. The POSterminal 200 sends to the bar-code reader 100 only an alarm signalindicating that no information has been retrieved from the merchandisefile 204. On the other hand, the POS terminal 200 of the presentinvention sends, for example, information about bargain merchandise tothe bar-code reader 100, which displays the information on the displayunit 46.

The merchandise file 204 stores various pieces of merchandiseinformation such as the names, codes, discount prices, etc., of articlesto be discounted for a predetermined period of time. These pieces ofinformation are displayed on the display unit 46 of the bar-code readerof the present invention.

FIG. 17B shows a flow of data according to the present invention. ThePOS terminal 200 sends to the bar-code reader 100 information aboutmerchandise prices and services to be displayed on the display unit 46.An information output unit 203 prepares information to be displayedaccording to the contents of the merchandise file 204 and instructionsfrom a higher apparatus.

When the time to start a bargain sale comes, the POS terminal 200retrieves the names and prices of articles to be discounted from themerchandise file 204 and sends the data to the bar-code reader 100. Thebar-code reader 100 displays the data on the display unit 46. As aresult, the operator may confirm the details of the bargain articles onthe display unit 46.

The merchandise file 204 also stores usual bargain articles. When theshop is opened, the POS terminal 200 retrieves information about thebargain articles from the merchandise file 204 and transfers theinformation to the bar-code reader 100. The bar-code reader 100 displaysthe information on the display unit 46.

After the bar-code reader 100 reads a bar code, the POS terminal 200displays the commodity name, price, etc., related to the bar code. Whenreading a bar code, the operator must see the bar-code reader 100, andwhen confirming the commodity name and price related to the bar code,the operator must see the display of the POS terminal 200. If the POSterminal is away from the bar-code reader due to the layout of thecheck-out counter, the operator must move his or her eyes between thebar-code reader and the POS terminal. In this case, it is difficult forthe operator to quickly confirm the messages on the display of the POSterminal 200.

The bar-code reader of the present invention has the display unit 46 todisplay the commodity name, price, etc., of an article whose bar codehas been just read. It is easy for the operator to carry out a bar-codereading operation, and at the same time, check messages displayed on thedisplay unit 46.

Upon receiving bar-code data from the bar-code reader 100, the POSterminal 200 retrieves information such as commodity name and pricerelated to the bar-code data from the merchandise file 204. The POSterminal 200 displays the information on the display of-its own, and atthe same time, sends the information to the bar-code reader 100. Thebar-code reader 100 displays the information on the display unit 46.

The POS terminal 200 or a higher apparatus may send various kinds ofinformation, instructions, and guides to the bar-code reader 100. Thebar-code reader 100 displays these pieces of information on the displayunit 46, which is easily seen by the operator.

The display unit 46 must not interfere with a laser beam emitted fromthe laser source or reflected light from a bar code. When the displayunit 46 is thick, the bar-code reader must be also thick so that thedisplay unit 46 may not interfere with the emitted and reflected light.To reduce the thickness of the bar-code reader, the display unit 46 mustbe thin. For example, a liquid crystal panel is preferable for thedisplay unit 46.

FIG. 18 shows a check-out counter having a bar-code reader 100 and a tagnullification unit 400 according to a prior art.

To prevent shoplifting, a magnetic tag is attached to each article. Ifthe article is illegally brought out of the shop, a detector at the exitof the shop detects the tag and issues an alarm. After the article islegally purchased, the tag must be nullified. The prior art of FIG. 18arranges the bar-code reader 100 and tag nullification unit 400 side byside on the check-out counter 500. The nullification unit 400 isselected according to the kind of tags.

An article is passed along the bar-code reader 100 to read the bar codeof the article and is moved over the nullification unit 400. Namely, thetag of the article is nullified just after reading the bar code of thearticle. It is preferable to integrate the bar-code reader 100 and tagnullification unit 400 to save space and cost.

FIG. 19A shows a bar-code reader 100 incorporating a tag nullificationunit 400 according to a prior art. The bar-code reader 100 has a window9 around which the nullification unit 400 is arranged. The nullificationunit 400 is, for example, a magnet.

This prior art nullifies the tag of an article before scanning the barcode of the article. It is not clear for the operator whether the barcode of the article has been read or only the tag has been nullified.Accordingly, this system is not effective to prevent shoplifting. Thenullification unit 400 is too close to the window 9, and the areathereof is too small, so that the nullification operation is difficult.

FIG. 19B shows the movements of an article when the bar code thereof isread and the tag thereof is nullified by the bar-code reader of FIG.19A. To read the bar code, the article must skip the nullification unit400. After the bar code is read, the article is lowered close to thenullification unit 400. To ensure the nullification of the tag, thearticle must be repeatedly passed over the nullification unit 400.

FIG. 20 shows a bar-code reader, according to the fifth embodiment ofthe present invention, which solves the problem of the prior art. Thebar-code reader has a cover 61. In a free space of the cover 61, a tagnullification unit 400 is formed beside a window 9. The window 9 isformed on the right side of the bar-code reader, and the nullificationunit 400 is on the left side thereof. The area of the nullification unit400 is relatively large. An article is first passed above the window 9and then above the nullification unit 400. Namely, the tag of thearticle is nullified after the bar code thereof is read.

FIG. 21 is a side view showing the bar-code reader of FIG. 20. Anarticle 300 is passed above the window 9, to read the bar code thereof.Thereafter, the article 300 is brought close to the nullification unit400 to nullify the tag thereof. The operator is not required to avoidthe nullification unit 400 when reading the bar code, nor to repeatedlypass the article 300 above the nullification unit 400. This results inimproving the efficiency of the operator.

Some tags must be touched with the tag nullification unit 400 when theyare nullified. On the other hand, an optimum position to read a bar codeis slightly away from the window 9 due to the focal point of a scanningbeam. In FIG. 21, the article 300 is passed above the window 9 to readthe bar code thereof. To nullify the tag of the article 300, the articleis lowered so that the tag may be in contact with the nullification unit400. In this way, the height at which the bar code is read differs fromthe height at which the tag is nullified. This may deteriorate theefficiency of the operator.

To solve this problem, the height of the nullification unit 400 may beincreased to the height where bar codes are read so that the tag of anarticle is naturally nullified by the nullification unit 400 after thebar code thereof is read.

FIGS. 22 and 23 show a bar-code reader according to the sixth embodimentof the present invention with a raised tag nullification unit 400. FIG.22 is a perspective view and FIG. 23 is a side view. The nullificationunit 400 is higher than a window of the bar-code reader and is inclinedin an article passing direction.

FIG. 23 shows the movement of an article 300 whose bar code is read andwhose tag is nullified. The article 300 is moved linearly, downwardly,and obliquely. As a result, the bar code is properly read, and the tagis properly nullified by the nullification unit 400. Since thenullification unit 400 is inclined, the article 300 naturally gets incontact with the nullification unit 400. This results in improving theefficiency of the operator.

In FIG. 23, the height of the nullification unit 400 is fixed. Thebar-code reader may have a mechanism for adjusting the inclination andheight of the nullification unit 400.

FIG. 24 shows a bar-code reader according to the seventh embodiment ofthe present invention. The bar-code reader has an elastic material 401such as sponge on which a tag nullification unit 400 is arranged. Theelastic material 401 absorbs a shock when an article is touched with thenullification unit 400. For fragile articles, this arrangement preventsthe breakage of the articles when their tags are nullified.

FIG. 25 shows the back of a bar-code reader 100 according to the eighthembodiment of the present invention. The back is provided with aconnector to which a cable is connected. The cable is connected to a POSterminal. The back is also provided with an adapter for supplying powerto the bar-code reader.

The connector is covered with a cable cover 71 to prevent the cable fromcatching something or from coming off. The cable cover 71 provides agood appearance.

The bar-code reader 100 may be installed vertically or horizontally.When it is arranged horizontally, a window will be on the right or leftside of the operator. To deal with such installation options, the cablecover 71 has three cable holes.

FIG. 26 shows the bar-code reader of the eighth embodiment with thecable 75 being pulled out of a cable hole 73. When the bar-code reader100 is vertically arranged, it is preferable to pull the cable 75 fromthe bottom of the bar-code reader. In this case, the cable 75 may bepulled out of a cable hole 73a on the short side of the cable cover 71.If the bar-code reader is installed such that the cable 75 is hardlypulled out of the bottom, the cable 75 may be pulled out of a cable hole73b on the long side of the cable cover 71.

When the bar-code reader is vertically arranged, the cable 75 may bepulled out of the cable hole 73a or 73b depending on the situation.

The bar-code reader according to the present invention may be installedon a check-out counter 500 (FIG. 35). In this case, the cable maydeteriorate the outside appearance of the bar-code reader and interferewith the operator. Accordingly, the bar-code reader of FIG. 26 has aspace (a recess) 74 on the back of the bar-code reader.

Clips 72 fix the cable in the recess 74. The clips 72 may be integralwith the casing of the bar-code reader. The clips 72 prevent the cablefrom sagging.

FIG. 27 shows a bar-code reader having a speaker hole 82 and a cover 61having a speaker hole 81 according to a prior art.

After correctly reading a bar code, the bar-code reader emits a soundfrom a speaker. The speaker is arranged under the speaker holes 81 and82. The cover 61 has a window 91 corresponding to a window 92 of thebar-code reader. The window 91 protects the window 92 and is replaceableif it is broken.

The cover 61 entirely covers the bar-code reader and has the speakerhole 81 corresponding to the speaker hole 82 of the main body.

These speaker holes 81 and 82 may conduct water inside the bar-codereader. Some articles having bar codes to be read by the bar-code readermay be wet or contain liquid. When reading these articles, water maydrop on the bar-code reader and enter the inside thereof through thespeaker holes to cause malfunctions in the bar-code reader.

If the speaker hole 81 of the cover 61 is eliminated to prevent suchtrouble, the volume of sound will be insufficient for the operator.

FIG. 28 shows a bar-code reader according to the ninth embodiment of thepresent invention to solve this problem. The bar-code reader is coveredwith a cover 61. The cover 61 has a glass window 91 and no speaker hole.Accordingly, no water can enter the bar-code reader through the cover61.

The top of the bar-code reader has a buzzer hole 82 under which a buzzeris arranged. When the buzzer makes a sound, the sound is propagatedthrough the hole 82. The buzzer may be a speaker.

The volume of the buzzer sound coming through the cover 61 may beinsufficient because the cover 61 has no hole. To solve this problem,the bar-code reader of FIG. 28 has a space between the bar-code readerand the cover 61, so that the buzzer sound may resonate in the space. Inaddition, each side face of the bar-code reader has a step to propagatethe buzzer sound outside through a gap formed by the step. FIG. 29 is aside view showing the bar-code reader of FIG. 28.

The top surface of the bar-code reader has four supports 83 forsupporting the cover 61 with the space 85 being secured between thebar-code reader and the cover 61. The height of the supports 83 isdetermined according to the volume of the space 85 required to providean optimum resonance effect for the frequency of the buzzer sound.

As indicated with arrow marks in FIG. 29, the buzzer sound is propagatedthrough the steps 84 of the bar-code reader. When the bar-code reader ishorizontally installed, water will not enter the bar-code reader throughthe steps 84. When the bar-code reader is vertically installed, thesteps 84 are vertically oriented. Even in this posture, water fromarticles will not enter the bar-code reader through the steps 84 becausethe articles are passed in front of the bar-code reader.

FIG. 30 shows the relationship between the wavelength (frequency) of abuzzer sound and the volume thereof. The volume reaches a maximum at apredetermined wavelength "a," and before and after the wavelength a, thevolume quickly drops.

A shop usually uses many bar-code readers. If they produce buzzer soundsof the same frequency, an operator may not distinguish the buzzer soundof its own from others. If the wavelength of the buzzer sound is changedto "b" in FIG. 30, the volume of the sound will be insufficient for theoperator.

To solve this problem, the present invention provides a bar-code readerwith buzzers having different wavelength characteristics. The buzzersare switched from one to another according to a request.

FIG. 31 shows a bar-code reader having a plurality of buzzers accordingto the 10th embodiment of the present invention. FIG. 32 shows thewavelength characteristics of the buzzers. The buzzer 86-1 has awavelength characteristic A, which is lower than the wavelengthcharacteristic B of the buzzer 86-2. Any one of the buzzers provides aproper volume of sound according to its characteristic curve, so that anoperator may clearly hear any one of the sounds.

The number of buzzers is not limited to four. Any number of buzzers maybe arranged depending on an installation space. Each buzzer may providea sufficient volume of sound at its peak wavelength so that the operatormay clearly hear it.

FIG. 33 shows a bar-code reader according to the 11th embodiment. InFIG. 28, the gap between the-cover and the body is on the long side ofthe body. The gap may be blocked by a check-out counter depending on theinstallation conditions of the bar-code reader. If the gap is blocked, abuzzer sound will not be propagated outside. The 11th embodiment solvesthis problem.

The bar-code reader of FIG. 33 has a buzzer 86-1 whose sound ispropagated upward as well as a buzzer 86-2 whose sound is propagatedsideward. A cover 61 of this bar-code reader is channel-shaped.

FIG. 34 shows the bar-code reader of FIG. 1 of the prior art installedon a check-out counter 500. The window of the bar-code reader is tall,and therefore, part of the bar-code reader must be embedded in thecheck-out counter 500.

FIG. 35 shows a bar-code reader according to the 12th embodiment of thepresent invention. This bar-code reader is low, and therefore, it isconvenient to use without embedding the same in a check-out counter 500.To easily read a bar code, the scanning range of a scan beam must bewide to cross the check-out counter 500. Since the bar-code reader islow, the scan beam thereof easily crosses the check-out counter 500.Accordingly, a bar code of an article is surely read only by passing thearticle on the check-out counter in front of the bar-code reader.

FIGS. 36A and 36B show a bar-code reader on which a keyboard is placedaccording to a prior art, and FIGS. 37A and 37B show a bar-code readeron which a keyboard is placed according to the 13th embodiment of thepresent invention.

The bar-code reader of the prior art is tall, and the top thereof isspaced away from a window thereof. Accordingly, the difference Z betweenthe height X where a bar code is read and the height Y where thekeyboard is manipulated is large. To touch the keyboard, the operatormust extend his or her hands above the bar-code reading position. Thisis laborious for the operator.

On the other hand, the bar-code reader of the POS terminal of the 12thembodiment of FIGS. 37A and 37B is low. The difference R between thewindow and top of the bar-code reader is small. Accordingly, theoperator may easily reach the keyboard on the bar-code reader.

As explained above, the present invention provides a bar-code readerhaving a laser source, photosensor, and condensing lens that areunitized. The unit requires no adjustments of respective parts andsuffers no accident due to static electricity when it is replaced.

The photosensor is closer to the condensing lens from the focal point ofthe condensing lens, to stably read bar codes irrespective of thepositions of the bar codes.

The bar-code reader has a space to insert a memo. The bar-code readermay have a display unit for displaying information in response toinstructions from a higher apparatus. The memo space and display unitare easy to see and are used to indicate merchandise information. Thedisplay unit is useful to display timely information necessary for theoperator.

A tag nullification unit is arranged beside a window of the bar-codereader, to nullify the tag of an article after reading the bar codethereof. The nullification unit is higher than the window, so thatarticles are linearly moved for the bar-code reading and tagnullification operations. The nullification unit may be obliquely raisedwith respect to the window, to nullify the tag of an article afterreading the bar code thereof through natural movements. Thenullification unit may be installed on an elastic material to absorb ashock on the nullification unit when an article is brought in contactwith the nullification unit. This prevents the breakage of the article.

The bar-code reader has a connector covered with a cable cover toprevent a cable connected to the connector from coming off. The cablecover has a plurality of cable holes so that the cable is alwaysproperly pulled out of the cable cover irrespective of the settingsituation of the bar-code reader. The back of the bar-code reader mayhave a recess to receive the cable, as well as fittings to neatly fixthe cable and prevent the sagging of the cable.

A buzzer sound produced by the bar-code reader resonates between the topsurface of the bar-code reader and a cover. The top surface of thebar-code reader and the cover have no buzzer holes, and the side face ofthe bar-code reader has an opening to secure a required volume of buzzersound. The bar-code reader may have a plurality of buzzers havingdifferent sounds, so that the sound of each bar-code reader isdistinguishable from any others.

What is claimed is:
 1. A replaceable emission-condensing unit for a barcode reader including scan means having reflecting surfaces, the scanmeans for scanning a bar code with a laser beam according to apredetermined scanning pattern, the bar code reader also having a windowfor passing the laser beam from the scan means toward the bar code thatis present or being moved in the vicinity of the window, saidreplaceable emission-condensing unit comprising:a laser source foremitting said laser beam; condensing means for condensing reflectedlight returned from the bar code which passes through the window and isreflected by the reflecting surfaces of said scan means along a routetraced by the laser beam; and a photosensor for detecting the condensedlight and providing an electric signal in proportion to an intensity ofthe detected light, wherein said replaceable emission-condensing unitintegrally incorporates said laser source, said condensing means andsaid photosensor, configured to be mechanically correctly installed inthe bar code reader, and wherein the scan means is separate from saidreplaceable emission-condensing unit.
 2. A replaceableemission-condensing unit according to claim 1, further comprising a pairof mirrors which align an optical axis of the laser beam onto an opticalaxis of the reflected light.